Rite in the Rain All-Weather Polydura Field Books are manufactured with true outdoor durable components. The cover, the paper, the sewn-in pages, and even the glue is made to withstand the elements. This is a PolyDura Hard Bound book with 4 3/4" x 7 1/2" sewn pages. Polydura covers are a smooth plastic material made with post-consumer waste. They're virtually indestructible.